In 1977, as Voyager activity was building toward autumn launch, a struggle was underway in Washington to obtain approval for the new Jupiter orbiter and probe mission. Budgeting authority was requested in the President’s Fiscal Year 1978 budget, but only after extensive testimony and several Congressional votes was the mission approved. The official new start for JOP, soon to be renamed Galileo, was set for July 1, 1977, and the scientific investigators and their instruments were selected in August. At JPL, many members of the Voyager Team made a smooth transition to the Galileo Project. Much of the knowledge that had gone into the design of the Voyager spacecraft and its subsystems was now incorporated into Galileo. Similarly, at Ames the knowledge gained from the design of the Pioneer Venus probes, which were launched to Venus in 1978, a year after Voyager launch, was applied to design of a Jupiter probe. Among the individuals who brought their Voyager experience to Galileo were John Casani, who left the position of Voyager Project Manager to become Galileo Project Manager, and Torrence Johnson of the Voyager Imaging Team, who became Galileo Project Scientist. The Scientific Capability of Galileo The investigations of Jupiter and its system planned for the Galileo Project represented substantial advances over those carried out by Voyager. In part, this was the result of new spacecraft capabilities, particularly the atmospheric entry probe. It also represented increasing sophistication in scientific instrumentation over the seven-year interval between the selection of the payloads for the two missions. The main emphasis in the study of Jupiter itself is on direct measurements with the Probe. For the first time it will be possible to examine directly the atmosphere of a giant planet. By measuring the temperature and pressure as it descends through the clouds, the Probe can determine the structure of the atmosphere with much higher precision than could ever be obtained from remote observations. The structure, in turn, provides information on dynamics—the circulation and heat balance of the Jovian atmosphere. In addition, the Probe can make direct measurements of the composition of the gases, with sensitivity in some cases to quantities as low as a few parts per billion. In addition to the elemental abundance, the amount of different isotopes can also be measured. Direct studies of the clouds of Jupiter can be made from the Galileo Probe. With a device called a nephelometer (literally, cloud-meter), the sizes and compositions of individual aerosol particles will be determined. An infrared instrument will determine the temperatures of the cloud layers and measure the amounts of sunlight deposited in different regions of the atmosphere. Another instrument will search for lightning; it has the ability to detect both the flash of light and the radio static generated by each bolt.